Palladium enolate umpolung: Cyclative diacetoxylation of alkynyl cyclohexadienones promoted by a Pd/SPRIX catalyst

Abstract

A novel palladium-catalyzed reaction involving an unusual nucleophilic attack on a palladium enolate was developed using a spiro-bis(isoxazoline) (SPRIX) ligand. Treatment of alkynyl cyclohexadienone substrates with a Pd/SPRIX catalyst in acetic acid under an oxygen atmosphere furnished diacetoxylated benzofuranone derivatives in good yields. This cyclative diacetoxylation proceeded enantioselectively in the presence of an optically pure SPRIX ligand. In a SPRIX: A new palladium-catalyzed reaction involving an unusual nucleophilic attack on a palladium enolate was developed using the SPRIX ligand. Treatment of alkynyl cyclohexadienone substrates with Pd/SPRIX in acetic acid under an oxygen atmosphere furnished diacetoxylated benzofuranone derivatives in good yields and with high enantioselectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.